#include <iostream>
#include <vector>
#include <cstdio>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

const std::string gsep = " ";
std::vector<int> data;

enum{ // 枚举
    OK = 0,
    OPEN_FILE_ERROR = 1,
};

int SaveBegin() //子进程备份, 返回值为退出码
{
    std::string name = std::to_string(time(nullptr));
    name += ".backup";
    FILE *fp = fopen(name.c_str(), "w");
    if(fp == nullptr) return OPEN_FILE_ERROR; // 文件打开失败无法备份
    
    // 备份写入文件
    std::string dataStr;
    for(auto d: data)
    {
        dataStr += std::to_string(d);
        dataStr += gsep;
    }

    fputs(dataStr.c_str(), fp);
    fclose(fp);
    return OK;
}

void Save()
{
    pid_t id = fork();
    if(id == 0) // 子进程
    {
        int code = SaveBegin();
        exit(code);
    }
    int status = 0;
    pid_t rid = waitpid(id, &status, 0);
    if(rid > 0)
    {
        int code = WEXITSTATUS(status);
        if(code == 0) printf("备份成功, exit code : %d\n", code);
        else printf("备份失败，exit code : %d\n", code);
    }
    else
    {
        printf("waitpid\n");
    }
}

int main()
{
    int cnt = 1;
    while(true)
    {
        data.push_back(cnt++);
        sleep(1); 
        // 每 10s 备份
        if(cnt % 10 == 0)
        {
            Save();
        }
    }
}

